 Every year, millions of visitors come to Washington, D.C. to tour the National Archives, the nation's largest storehouse of historic documents. This year marks the Constitution's 200th anniversary, and to help monitor the aging process of this document and others, like the Declaration of Independence and the Bill of Rights, the National Archives recently installed a space-age camera designed by NASA's Jet Propulsion Laboratory in Pasadena, California. The National Archives came to NASA with a request for NASA to take a look at what kind of technology could possibly be used to provide a long-term monitoring system that would allow them to have baseline information that was taken at the beginning of the monitoring period and then to be able to follow in a very detailed fashion the fate of the documents over the next 50 to 100 years. Chris Stevens' team, led by Ed Miller, designed the National Archives camera, adapting technology normally used for deep space missions. The camera images the documents by scanning, under green light, a handful of pre-designated postage stamp-size areas. In this case, a practice target is used instead of a real document. During each pass of the scanner, a million bits of digital information are collected. The system has the capability of going back year by year to the exact same spot in order to make comparative studies of the condition of the documents. In addition, a whole variety of image processing techniques can be used. In the case of the first two letters in the Constitution, the W and E of We the People, the black and white image can be color-enhanced to more easily see areas where ink has flaked off the function. There are other needs for the system according to Norville Jones of the National Archives Preservation Line. We have concern that changes do happen when documents are exhibited, that there can be fading or changes in contrast or paper can darken. And by getting a baseline reading before an item goes on exhibit and then monitoring it after exhibit and keeping records on items that are frequently requested that we'd be able to tell changes that were occurring before any serious damage had happened. The monitoring system can also be a valuable tool for determining what type of active measures to take in order to save and stabilize a document or piece of artwork. The imaging system represents a down-to-earth use of technology developed over the years for outer space probes like Voyager, which used it to capture incredible pictures of our nearby planets. Norville Jones sums up NASA's link with the past. At the time that the Constitution was created, pen and ink on parchment was about the most permanent and best that you can do. And I think now in honor of the 200th anniversary of the Constitution we're able to use what is I think now the best that you can do in terms of wrapping up new technology in order to be able to assure that the documents last not only 200 years longer but 2,000 years as long as we can imagine.